Thermostatic electrical control switch



Sept.- 22-, 1931. J. J. SHIVELY THERMOSTATIC ELECTRICAL CONTROL SWITCH Filed March 50, 1926 24. 2 4 INVENTOR.

ATTORNEY.

Patented Sept. 22, N 1931 PATENT OFFICE JOHN J. SHIVELY, F BROOKVILLE, PENNSYLVANIA THERMOSTATIC ELECTRICAL CONTROL SWITCH Application filed March 30, 1926. Serial No. 98,465.

This invention relates to thermostatically controlled switches for controlling electrical circuits including refrigerating machinery, electrical heaters, valve-operating devices for controlling heating or cooling fluid mediums,

highly effective in use with res ect to its sensitivity, accuracy and dependa ility.

S ecifically the invention contemplates the com ination with. a thermostatic element comprising a helix of bimetallic material for operating a rock shaft ofa mercury-contact switch of a known type carried by said shaft.

In another particular the invention contemplates the provision of improved mountings for the mercury-contact switch on a thermostatically operated rock shaft which will admit of easy and rapid adjustment of said switch on the shaft to set the switch for control at any desired temperature.

The foregoing and other objects are obtained by the construction disclosed in the accompanying drawings and the following more detailed description referring specifically thereto. It is to be understood that the invention is not limited to the specific forms thereof which are illustrated and described herein. as Of the accompanying drawings,

tion through a device embodying the invention; 7

Figure 2 is a front elevation thereof;

Figure 3 is a front elevation of a modified form of the invention;

' Figure 4 is a part section on line 44 of Figure 3;

Figure 5 is a front elevation of another form of the invention;

Figure 6 is a part section on line 6-6 of Figure 5';

Figure 7 is a plan of a strip of metal from which a switch mounting clip may be constructed;

Y Figure 1 is a longitudinal diametral see} Figure 8 is a front elevation of a clip made from the strip of Figure 7; and Figure 9 is a side elevation thereof.

Referring to the drawings, 10 illustrates the wall of a chamber containing a medium, 55 the temperature of which is to be controlled. Threaded into chamber 10, as at 11, is a: casing 12. containing a helix 13 of suitable bimetallic material-which is secured at one end as by being soldered into a slot 14 in a clo- ,60 sure 15 on the inner end of casing 12.

Mounted on the outer end of casing 12 out 'side of the wall 10 is an enlarged casing 16, and secured on the free end of helix 13 is a rock shaft 17 having a loose bearing in an aperture 18 through the inner wall of casing 16 and extending into said casing.

The portion of shaft 17 projecting into casing 16 is preferably knurled as indicated at 19's0 as to provide a gripping surface on which a mercury-contact switch 20 may be adjustably mounted by means of a spring clip 21 adapted to embrace the knurled portion 19 of the shaft. The clip 21 comprises a strip of spring metal formed with a body 7: portion 22; acentral tongue 23 on one end of the body portion; a pair of side tongues 24,

24 on the other end thereof defining a slot 25 in the other end through which tongue 24may pass; a laterally extending clip portion 26 for embracing the top of the tube of switch 20; and a short laterally extending clip portion 2:7 for assisting clip portion 26 in bolding the switch tube on the body portion 22 of the clip. The tongues 23 and 24 are bent downwardly and formed with reverse goose neck bends at 28 and 29 respectively, whereby by pressing the lower ends thereof together with the fingers the tongues may be slid into a gripping embrace on the knurled portion 19 of shaft 17. The clip portions 26 and 27 are bent to the condition shown in Figure 9 so as to grippingly embrace the tube of switch 20.

The switch 20 comprises the usual bulb 5 containing a globule of mercury 30 and having contacts 31, 31 adjacent one end thereof connected by leads 32, 32 to flexible leads 33, 33 which may extend upwardly out of casing 16 through a conduit 34 suitably 10! mounted on the casing. The front of casing 16 'may be enclosed by any suitable cover such as cover 35 andfsealed so as to be dustproof by a gasket as at 36.

In the forms of the invention shown in Figures 3 to 6, inclusive, the switch is 'so mounted as to be rockable on the clip through a small angle to give a quicker or sharper make or break of the circuit by the mercury globule 30. According to the form shown in Figures 3 and 4, the bulb of switch 20 is mounted in a U-clip 37 supported on a comparatively light ifiexible leaf spring 38 mounted on clip 21 and permitting a yielding rocking action of the bulb thereon, due to the influence of gravity on the unbalanced bulb. According to the form shown in Figures 5 and 6, a U-clip 39 for holding the "switch is loosely pivoted at 40 on clip 21.

It will appear from the foregoing that named spring clip being supported .on said mountin by a flexible eaf spring so as to be rocka le thereon.

2. A thermostatic, electric control device.

ab e to any desired angle thereon, and a spring clip on said mounting for holding a mercury contact switch therein, said lastnamed spring clip being rockably mounted on said mounting.

JOHN J. SHIVELY.

when the temperature of a'inedium effective 1 on casing 12 varies, the convolutions of the bimetallic coil 13 tighten up or unwind and since one end is fixed at 14 this action is transmitted to shaft 17, causing it to rock in one direction or the other. The instrument may be so calibrated that when any desired temperature of control is reached.the bulb will be so inclined that mercury globule30" will fl0w about contacts 31 .to makea circuit or flo'w away from contacts 31 to break a circuit including electrical devices controlling the heating or cooling medium.

This calibration may be easily effected since the clip 21 is easily adiustable to support the bulb 20 at any desired angle on shaft 17 by merely pressing the lower ends of tongues 23 and 24'toward each other turning the clip 21 in the desired direction and then releasing tongues '23 and 24.

Removal of the switch 20 from the device can be accomplished either by releasing clip 21 from shaft 17 orif it is desired to preserve the substantial position of calibration for any given purpose by removing the bulb 20 from clips 26 and 27 or the U-clips 37 or 38.

The operation of the forms shown in Figures 3 to 6 inclusive will be understood .from

what has already been described with reference' to these figures. The devices shown therein efl'ectivelyreduce arcing caused by the mercury. flowing too slowly under the slow action of the helix 13.

Modifications of the invention may be re- 3 bimetallic metal fixed at one end, of a shaft secured to the other end, a spring clip mount-- ingon the shaft so as to be readily adjustable to any desired angle thereon, and a spring clip on said mounting for holding a mercury contact switch therein, said last- 

